This is actually a much more difficult question than you may think.
Competitive bidding on a private construction project is legal. Competitive bidding on a public works project that operates to defeat the legally mandated secret and fair bidding process may be illegal.
I assume that your question concerns a private construction projection.
That said, a verbatim copy of a private bid, distributed to a third party is prima facie ("on its face") copyright infringement! Most construction businesses and materials suppliers would never consider this possibility, but that's the real cause of action, in my opinion. Damages for copyright infringement which arise before the author's work is registered with the U.S. Copyright Office is limited to actual damages (which would typically be lost profits).
The typical means of protecting against this sort of business practice, is to have the contractor sign a nondisclosure/confidentiality agreement before submitting a bid. But, if that's too difficult to accomplish, then copyright infringement would be the only means of recourse for the supplier against the contract.
It is good practice to place a copyright notice on a unique bid, and state that the license is limited to internal distribution by the intended recipient. That way, the contractor would have unambiguous notice that an unauthorized copy of the bid transmitted to a third party is subject to legal action for copyright infringement.
I hope I've answered your question. Please let me know if you require further clarification. And, please provide a positive feedback rating for my answer -- otherwise, I receive nothing for my efforts in your behalf.
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